During the information era, the Internet and the service of World Wide Web develop rapidly. Therefore, the wider and
wider bandwidth is required with the lower and lower cost. The demand of operation turns out to be diversified. Data,
images, videos and other special transmission demands share the challenge and opportunity with the service providers.
Simultaneously, the electrical equipment has approached their limit. So the optical communication based on the
wavelength division multiplexing (WDM) and the optical cross-connects (OXCs) shows great potentials and brilliant
future to build an optical network based on the unique technical advantage and multi-wavelength characteristic. In this
paper, we propose a multi-layered graph model with inter-path between layers to solve the problem of multicast routing
wavelength assignment (RWA) contemporarily by employing an efficient graph theoretic formulation. And at the same
time, an efficient dynamic multicast algorithm named Distributed Message Copying Multicast (DMCM) mechanism is
also proposed. The multicast tree with minimum hops can be constructed dynamically according to this proposed
This paper investigates the survivable traffic grooming problem for optical mesh networks employing wavelength-division multiplexing (WDM). While the transmission rate of a wavelength channel is high, the bandwidth requirement of a typical connection request can vary from the full wavelength capacity down to subwavelength. To efficiently utilize network resources, subwavelength-granularity connections can be groomed onto direct optical transmission channels, or lightpaths. Meanwhile, the failure of a network element can cause the failure of several lightpaths, thereby leading to large data and revenue loss. Fault-management schemes such as protection are essential to survive such failures. Different low-speed connections may request different bandwidth granularities as well as different protection schemes. How to efficiently groom such low-speed connections while satisfying their protection requirements is the main focus of our investigation. The paper tackles the dynamic survivable traffic grooming problems in multifiber wavelength-routed optical networks by representing the network as a layered graph model. This graph multi layers, where each layer represents a specific wavelength. Each link in the layered graph has more than one fibers and an associated cost. We use a modified Dijkstra algorithm that has a reduced complexity due to the structure of the layered graph. Heuristic algorithms for fiber selection based on a well-designed link-cost metrics are proposed. The performance of various routing algorithms is evaluated through simulation studies.
In this paper, we study the problem of dynamic survivable routing in optical networks with Shared Risk Link Groups (SRLG). Survivability and service continuity have been well recognized as the most important issues in the design of control and management planes for the next-generation optical networks with wavelength-division multiplexing (WDM) as the core technology. To make the connections survivable after various failure scenarios such as fiber cut and duct cut, it is necessary to consider SRLG diverse routing constraints in the traffic grooming problem. To jointly consider the working and backup paths, we first formulate the diverse routing problem into an Integer Linear Programming (ILP) process, in which the working and shared backup paths corresponding to a connection request are solved in a single step. We proposed failure-dependent SRLG protection heuristics algorithms for fiber selection. We compared the performance of various routing algorithms through simulation studies based on different metrics. Another contribution of this paper is a well-designed link-state metric is proposed for allocating the backup path and two selection schemes considering path costs are developed.
We consider the problem of routing and wavelength assignment problem (RWA) in wavelength-routed networks, which consists of the Wavelength Division Multiplexers (WDM) and optical cross-connect (OXCs) devices interconnected via point-to-point WDM links. Assume that none of the OXCs has wavelength conversion capability. In this paper, we develop a set of dynamic distributed source-based DLE algorithms to provide primary and backup paths for connection requests with protection guarantee under single-link failures with local information. For better resource utilization, we employ multiplexing techniques, named primary backup multiplexing, to maximize the wavelength sharing among independent protection lightpaths. This technique allows a wavelength channel to be shared by a primary and one or more backup paths. We formulate the problem in link-based restoration context. The algorithm support on-demand path computation. Another main contribution is the introduction of the light-weight aggregated link metrics termed "barrel", we provide guidance to construct the protection routes with minimal wavelength consumption. We also compare the performance of various routing algorithms through simulation studies.
Generalized Multiprotocol Label Switching (GMPLS), which is developed to support common control of packet, TDM, wavelength, and fiber services, is the key enabler of the new network model. The survivability of IP over WDM networks gains importance as network traffic keeps growing. In this paper, we propose an integrated provisioning scheme to dynamically allocate Label Switched Paths (LSPs) in IP over WDM networks. This scheme takes advantage of information sharing between layers (e.g., link state information, bandwidth usage, and protection capability) to eliminate redundancies and inefficiencies in the traditional layer-independent service provisioning. The integration of information is facilitated by GMPLS signaling. The proposed scheme also uses GMPLS capabilities to provide end-to-end survivability against network failures. The ability to provision across all network layers ensures efficient bandwidth usage. We propose two integrated routing algorithms: availability-based integrated routing algorithm and joint availability-based integrated routing algorithm. The simulation is made to evaluate the performance of our proposed integrated provisioning mechanism. As a result, network performance can be optimized over all layers. This could lead to significant cost savings for service providers.
We consider the problem of routing and wavelength assignment problem (RWA) in wavelength-routed networks, which consists of the Wavelength Division Multiplexers (WDM) and optical cross-connect (OXCs) devices interconnected via point-to-point WDM links. Assume that none of the OXCs has wavelength conversion capability. The paper shows that the problem of RWA can be solved simultaneously by employing an efficient graph theoretic formulation, named as multi-layered graph model. On the basis of this notion, a heuristic RWA algorithm for static case is proposed. The numerical examples confirm that the proposed approach for static lightpath establishment (SLE) can obtain better solution for the number of requested lightpaths. The paper also considers the dynamic lightpath establishment (DLE) problem. We propose another heuristic DLE algorithm based on alternate-lightpath routing, according to a global selection criterion. We make a comparison of blocking probability according to different selection criterion. The performance of the proposed DLE algorithms is also evaluated and compared with that of the conventional algorithm via simulation of an arbitrary mesh network, where lightpath requests are assumed to arrive according to a Poisson process with exponentially distributed holding times.